Palladium‐Catalyzed Cyclizative Borylation of Allenyl Ketones through Carbene Boryl Migratory Insertion: Access to Densely Substituted Furyl Boronates

Abstract

Herein the palladium-catalyzed cyclizative borylation of allenyl ketones with diboron compounds is reported which involves the carbene boryl migratory insertion as the key step. This reaction features mild conditions, good functional group tolerance and broad substrate scope. Thus, it represents an efficient methodology for the assembly of diverse tri-substituted furyl boronates. In addition, a series of transformations of the resultant multi-substituted furyl boronates were conducted to provide various densely substituted furan derivatives in good yields, further illustrating the potential synthetic utility of this methodology.

Palladium‐Catalyzed Oxidative Alkynylation of Allenyl Ketones: Access to 3‐Alkynyl Poly‐substituted Furans†

“…The reaction conditions in which we previously reported on palladium‐catalyzed oxidative cross‐coupling reactions between allenyl ketones and aryl boronic acids were first applied to the current reaction. [ 11 ] We were pleased to find that the alkynylated furan product 3a could be successfully isolated in 35% yield (Table 1, entry 1). Utilizing 1,4‐dioxane instead of toluene showed an obvious enhancement of reaction yield compared with other organic solvents (Table 1, entries 2—5).…”

“…The palladium carbene migratory insertion is proposed to be involved in above‐ mentioned coupling reactions as the key step (Scheme 1b). [ 11 ]…”

Synthesis of a Series of Methyl Benzoates through Esterification with a Zr/Ti Solid Acid Catalyst

“…For example, MB has a fruity flavor that can be used in pineapple, strawberry, and cherry syrups, and it as acts as a solvent in resin rubber. Additionally, p-methoxybenzoic acid is also used as a flavoring, and methyl p-bromobenzoate is the main raw material of pemetrexed disodium, an antitumor drug, and diglitin A [15], an antifungal compound [16][17][18].…”